Ureteral stents are widely used to facilitate drainage in the upper urinary tract (e.g., from the kidney to the bladder), for example, following ureteroscopy, endourerotomies, and endopyelotomy for ureteral strictures, as well as in other instances where ureteral obstruction may occur for example, following lithotripsy. Such stents, however, are commonly associated with pain and discomfort in the bladder and flank area after insertion. One way to minimize pain and discomfort is to orally administer drugs to the patient. Commonly prescribed oral drugs are opioid analgesia (e.g. Vicodin® and Percocet®), which are controlled substances and have the potential for abuse by patients.
Another way to address pain and discomfort is to release a therapeutic agent from the ureteral stent. See Pub. Nos. US 2003/0224033 to Li et al. and US 2006/0264912 to McIntyre et al.
Another way of addressing this pain is to use a softer material, particularly in forming the proximal end of the stent, which engages more sensitive tissue in the bladder region. Stents of this type may employ co-extrusion to combine a firm durometer EVA copolymer at the distal end, which improves stent advancement, and a soft durometer EVA at the proximal end, which improves comfort. A specific example of such a stent is the Polaris™ Dual Durometer Percuflex® Ureteral Stent with HydroPlus™ Coating, Boston Scientific, Natick, Mass., USA.